Manufacture of chromic acid.



UiiTlilD i i i'li lilhl ll ROBERT SUCHY, OF BI'lZlERFltLD, GERMANY, ASSIGNQR TO CHEMISQHE -FABRlK Gi'llESHElli l 'ELEUFRGN. F RANKFORT-ON-TH HMAIN, GER

MANY, A GUR-PQliAilON OF GERB'IAN Y. I

MANUFACTURE OF one-locale ACiD.

Specification of Letters Patent.

'Iatented Jan. 15, 190?.

Application filed November 9, 1906, Serial No. 342.759.

To all whom, it nil/,1 concerns Be it known that 1, ROBERT Scour, a sub- Je'ct of the Emperor of AustriwHungary, re-

siding at Bi tterfeld, Germany, have invented chromic acid from alkali chrometes, alkali bichromstes, and chromic acid containing sulfuric nerd- Chrornic acid has already Y been extracted from the said compounds by fi'QllVGI'tlIlg the bodies combined with the ehromic acid into bisulfate ;'but the difilculty experienced in obtaining chromic Vecid by this meanshes been the separation .of the chromic acid from the bisulfate, which has been a very troublesome and lengthy oper- 21.51011. Y

- The object of thisinvention is to effect this separation in a simple manner and in a short time endnrith the use of ver simple apparatus. The mixture of' chromic acid and bisulfate is in accordance with this invention heated to the melting-point, this resulting in the formation of two fluids that are not miscible with each other and can therefore be easily separated from each other by mechanical means The invention may, for example, be car ried out as fullOWSI In any suitable vessel one hundred kilograms of sodium'hichronmte coarsely powdered are mixed with sixty-scven kilograms of sulfuric acid of 655 Baum and heated while being stirred. Water is first evaporated, the mass becoming hard and pulverulent end on being further heated becomes a pulp or paste of molten hisulfete and solidv chromic acid. The temperature is then raised until all the solid portions are melted, and the mass is allowed to cool down. to 150 Centigrade. The hisulfotc and the chromic acid will then have separated, and the bisulfete isremoved in any usual manner. remaining chromic acid is deprived by me chemical means of the bisulfate adhering-to it and broken into pieces which do not contein more than from one and one-half to two per cent. of bisulfate.

7 When chromic acid is to he obtained from potassium hiohrornate, the process followed is similar. In obtaining chromic acid from its mixture with sulfuric acid the sulfuric acid is converted into bisuiiete by means oi an elkali salt.

By the process according to this invention it is possible ine single operation to isolate the chromic acid in sleigh state of purity, whereas hitherto from three to four operations have been needed and yet the chromic acid has still been very impure owing to the presence of sulfuric acid,

1 claim I The herein-described process of manufacturing chromic acid which consists in mixing a chromete with sulfuric acid, heating themixt'ure whereby chromic acid and e bisulia-te are formed and Watereveporeted, then fusing the mixture by heat and separating Roeen'r sneer.

'Witncsses: I I

llims'r Borcsnzicn, Aooos'r Union.

The 

